1. Field of the Invention
The present invention relates to a balloon catheter, a medical apparatus, a method for treating a living organ and a use of the medical apparatus for treating a living organ. More particularly, the present invention relates to a balloon catheter which can cure a diseased tissue by heating and cooling a living organ in a very short time and, in particular, can expand a blood vessel without causing damages when the balloon catheter is used in the percutanuous transluminal coronary angioplasty, a medical apparatus comprising the balloon catheter, a method for treating a living organ using the balloon catheter and a use of the medical apparatus for treating a living organ.
2. Description of Related Art
The percutanuous transluminal coronary angioplasty (PTCA) using a balloon is being widely conducted recently. In the period shortly after the introduction of the technology, examples of the operation in which PTCA was applied and the diseases to which PTCA could be applied were rather limited. Due to the progress in instruments and technology, the application of this technology has been expanded not only to multivessel diseases but also to complete occlusion and acute myocardial infarction. However, the frequency of recurrence of stenosis is great, and this is considered to be the greatest problem of PTCA. To prevent the recurrence of stenosis, various stents have been developed and used. However, the effect of preventing the recurrence of stenosis is limited, and the presence of the remaining stent occasionally works as an obstacle for the treatment. Moreover, stainless steel used as the material of the stent occasionally exhibits allergic effects to the tissue. Therefore, it has been desired that stenosis is treated without using a foreign substance such as stainless steel and the recurrence of stenosis is prevented. Heretofore, it has been tried that a tissue of a tubular organ is burned or vaporized directly by a laser treatment or that the portion of stenosis is treated with argon laser beams. However, these trials failed without significant effects due to formation of serious damages to tissues or adverse effects of decomposition products.
It is considered that, when a cell of a smooth muscle is damaged and the tissue is restored by the stem cell, abnormal information due to the damage is transferred or abnormal division of a stem cell takes place, and the recurrence of stenosis of a tubular organ takes place. It is occasionally conducted that a blood vessel for the treatment is cut by a so-called transluminal extraction catheter (TEC) or a rotablator so that the outer membrane alone is left remaining, and a stent is disposed thereafter. When a necessary tissue is removed by the cutting, the tissue of the inner skin is not stabilized even when the tissue is formed, and this is considered to cause the recurrence of stenosis. Since a blood vessel is forced to expand by a pressure as great as 800 to 1,000 kPa in the ordinary PTCA, the tissue is torn or the tissue of the blood vessel is degraded by the great force. Therefore, the recurrence of stenosis tends to take place due to excessive growth of the cells of the smooth muscle during the restoration of the coronary artery.
The development of instruments and methods for expanding a blood vessel without causing damages to the blood vessel at the portion of stenosis have been conducted. For example, as the apparatus useful for applying heat to the inside of the body of a patient in a treatment such as the treatment for forming blood vessels, a system for expanding a tubular organ in the body having a means for controlling a catheter which applies heat and pressure to a tissue of a tubular organ simultaneously, detects the change in the behavior of yielding or the change in the thermal conductivity of the tissue of the tubular organ, and react to the behavior of the tissue, is proposed (Japanese Patent No. 2984056, page 2). However, it is very difficult that the physiological reaction of a portion of disease in a very different diseased condition in each case is examined under a single criterion and the most suitable treatment is applied to the portion of disease. In PTCA, as the catheter which can solidify the inner face of a blood vessel by heating to prevent recurrence of stenosis without causing damages on the inner membrane of the blood vessel, a catheter equipped with a balloon made of a fluororesin and having a heating tube absorbing laser beams and a laser fiber protruding into the balloon, is proposed (Japanese Patent No. 2535250. pages 1 and 2). However, the thickness of the blood vessel tends to decrease when the inner wall of the blood vessel is heated at 80 to 90° C. As the catheter which prevents excessive local heating of the inside of the balloon, a catheter which has a heating tube having a metal braid and a resin tube covering the metal braid and two thermocouples in the balloon, is proposed (Japanese Patent No. 2864094, pages 1 and 2). However, this catheter has a problem in that it is difficult that a excellent result is obtained with stability when an excessively great force or an excessively great invasion of heat is applied to a blood vessel.